My parents bought a lot in a housing development near Hilo with the idea of maybe retiring to Hawaii. It was on a lava field. The lot was overgrown with weeds, and walking around through the weeds was particularly difficult because of the pitted surface. The surface needs to be bulldozed to make a decent yard. The insurance companies won’t pay out for lava flows, but will for fires(the catch is, you are evacuated and can’t prove that your house burned down before the flow reached it.)